The acquisition of physiological biometric features such as facial and ocular features is a necessary step in most biometric recognition applications (e.g., facial recognition, iris recognition, and the like). Several factors, however, make it difficult for conventional systems to acquire images of the quality necessary to ensure good recognition results. For instance, if the subject is in motion or is far away, or if the ambient lighting conditions are poor, the image captured may be unusable due to motion blur and/or poor focus. These difficulties are amplified if the biometric features of interest are particularly small, as is the case with the human iris.